Internal combustion engine with crankcase compression



y 1954 R. c. HEIDNER 3,132,635

INTERNAL COMBUSTION ENGINE WITH CRANKCASE COMPRESSION Filed July 50, 1962 INVENTOR. fax/4K0 6, 4 50/1456 AMMWQ lrrazvznc United States Patent ()fiice Patented May 12, 1964 Filed July 30, 1962, Ser. No. 213,240 12 Claims. (Cl. 12373) The invention relates to two stroke, internal combustion engines. More particularly, the invention relates to and is directed to an arrangement for conducting such oil as normally accumulates in the sump or bottom of the crankcase to the combustion chamber, whereby such oil is burned to produce power and is continuously discharged from the engine.

The invention utilizes the cyclical pressure condition which is produced in the separate crankcases of a two stroke engine by reason of piston movement and provides a conduit and valve arrangement connecting the sump of such a crankcase with an intake or bypass port which is formed in the cylinder wall and which constitutes a part of a bypass or transfer passage for conducting a combustion air-fuel mixture from the crankcase to the cylinder.

As a result, the cyclical pressure condition created in the crankcase serves to pump oil accumulated in the crankcase into the combustion chamber for over piston lubrication and ultimate burning and exhausting.

The invention is applicable both to single cylinder and multiple cylinder engines. In multiple cylinder engines the preferred form of the invention provides for a check valve and conduit connecting the sump of one crankcase to the bypass port of an oppositely acting cylinder so that the accumulated oil is ejected into the conduit from the crankcase during'the high pressure condition which exists in the crankcase incident to movement of the piston toward bottom dead center. The oil thus ejected into the conduit is pumped into the transfer passage in the area of the bypass port during the concurrent movement of the other piston toward top dead center. When the other piston subsequently approaches bottom dead center, the

bypass port is opened and the oil drained from the conduit is carried into the cylinder by the flow of the combustion air-fuel mixture. In addition, the flow of the mixture through the transfer passage into the combustion chamber also creates a pressure condition which tends to drain or siphon oil from the conduit for discharge to the combustion chamber. The check valve is utilized at the sump opening to prevent return flow consequent to a subsequently created subatmospheric pressure condition in the associated crankcase.

In single cylinder engines, the conduit and valve arrangement also includes a reservoir or auxiliary sump, which reservoir can be either open to the atmosphere or of an expandable nature and serves to collect such accumulated oil as is discharged from the crankcase in response to piston movement toward bottom dead center. The oil thus collected is sucked or pumped from the reservoir and drained into the transfer passage in the area of the bypass port during movement of the piston toward top dead center. When the bypass port is subsequently opened in response to approach of the piston to its bottom dead center position, the drained oil is carried into the combustion chamber by the flow of the combustible mixture. In addition, such flow also creates a pressure condition at the end of the conduit tending to drain or siphon oil from the conduit. As is the case with the multiple cylinder engine, check valves are employed to prevent back-flow to the crankcase. Increased discharge efficiency from the reservoir can be obtained by including a restriction in the line leading from the reservoir to the bypass port.

Other objects and advantages of the invention will become known by reference to the following description and the accompanying drawings of three embodiments of the invention.

In the drawings:

FIGURE 1 is a diagrammatic view, partially in section, of an alternately acting, twin cylinder, two stroke, internal combustion engine 11 embodying various of the features of the invention;

FIGURE 2 is a diagrammatic view, partially in section, of a single cylinder, two stroke, internal combustion engine 111 embodying various of the features of the invention; and

FIGURE 3 is a diagrammatic view, partially in section, of a single cylinder, two stroke, internal combustion engine 211 incorporating a modified arrangement embodying various of the features of the invention.

The engine 11 includes a conventional engine block 13 incorporating two cylinders 15 and 17, two respectively associated crankcases 19 and 21, a crankshaft 23 extending through the crankcases, separate pistons 25 and 27 reciprocably movable in the respective cylinders 15 and 17,

and connecting rods 29 and 31 respectively joining the pistons 25 and 27 to the crankshaft 23 in such manner as to effect opposite action of the pistons. Also included in the engine 11 are spark plugs 33 and 35 and bypass or transfer passages 37 and 39 respectively connecting the crankcases 19 and 21 to the combustion chambers, which transfer passages include respective ports 41 and 43 in the wall of the cylinders. As is common practice, the crankcases 19 and 21 are closed except for connection to the respective transfer passages 37 and 29 and for communication through suitable check valve means (not shown) such as conventional reed valves, with means for supplying a combustion air-fuel-lubricant mixture (not shown), such as a carburetor or the like.

In accordance with the invention, each of the crankcases 19 and 21 is formed to provide respective drains 45 and 47 at the low point or sump thereof. The drains are respectively opened and closed to control communication with respective conduits or lines 49 and 51 by suitable one-way check valve means 53 and 55. The check valves 53 and 5S operate to permit flow of accumulated oil from the associated crankcases during conditions of positive pressure therein and to prevent return flow to the crankcases during conditions of negative pressure therein. The conduit 49 terminates. at a nozzle or orifice 57 located in or adjacent to the intake port 43 associated with the cylinder 17, while the other conduit 51 terminates at a nozzle or orifice 59 located in or adjacent to the intake port 41 associated with the cylinder 15.

Pumping operation from each of the crankcases 19 and 21 to the opposite cylinders '15 and 17 is identical. Ascordingly, only the pumping operation from the crankcase 19 through the conduit 49 to the cylinder 17 will be described. As the piston 25 approaches bottom dead center, the positive pressure thus created in the crankcase forces such oil as may have accumulated in the sump through the check valve 53 to the conduit 49.

As the disclosed engine 11 is an oppositely acting engine, when the piston 25 is moving toward bottom dead center, thereby creating a positive pressure in the crankcase 19, the other piston 27 is moving toward top dead center, thereby creating a negative pressure in its associted crankcase 21. This negative pressure condition is communicated through the associated transfer passage 39 to the nozzle 57 at the end of the conduit 49, thereby tending to suck or withdraw oil previously delivered to the conduit 49 in response to movement of the piston 25 toward bottom dead center. When the piston 25 subsequently moves toward top dead center, the check valve 53 is closed, while the intake port 43 is opened in response to movement of the piston 27 toward bottom dead center. The resulting relief of the positive pressure condition thus created in the crankcase 21 causes a flow of combustion air-fuel mixture through the transfer passage 39 into the cylinder 17, carrying with such flow any oil which has drained from the nozzle 57. Such flow of the combustion air-fuel mixture through the intake port 4-3 also serves to create a pressure condition which drains or siphons oil from the conduit and to carry such discharged oil into the combustion chamber.

While the above disclosure has been made with respect to a two cylinder engine, it is obvious that the principles can be applied to any multiple cylinder engine having a sequential firing order.

In FIGURE 2, the engine 111 includes a cylinder 115, a spark plug extending into the cylinder 115, a piston 125 reciprocably movable in the cylinder 115, and a crankcase 1 19 which extends from the cylinder 115 and is closed except for a combustion air-fuel mixture intake (not shown), such as, for instance, a reed valve connected to a carburetor, and for a transfer or bypass passage 137 including an intake port 141 in the wall of the cylinder 115. Extending through the crankcase 119 is a crankshaft 123 joined by a connecting rod 129 to the piston 125.

in accordance with the invention, the crankcase 119 is provided at its lowest point or sump with a drain 145 communicating through a one-way check valve 153 with a conduit 14-9 leading to an oil collecting receiver or reservoir 161 which is open to the atmosphere, as indicated at 166. in operation, when the piston 125 travels toward bottom dead center, the accumulated oil in the sump is discharged through the drain 145, valve 153, and conduit 149 to the reservoir 161. Return flow of oil to the crankcase 119 is prevented by the check valve 153.

The reservoir 151 is also connected through a second one-way valve 163 through a conduit or line 165 terminating in a nozzle or orifice 157 in the intake port 141 connecting the transfer passage 137 to the cylinder 115. The one-way valve 163 functions to permit flow from the reservoir 161 and to prevent back flow. As a result, when the piston 125 is traveling toward top dead center, thereby creating a negative pressure in the crankcase, such pressure condition is communicated through the transfer passage 137 to the intake port 141 and acts upon the nozzle 157, thereby tending to drain oil from the conduit 165. As the piston approaches bot-tom dead center, the intake port 141 is opened and the resulting flow of combustion air-fuel mixture carries the oil drained from the conduit during the suction stroke of the piston 125 to the cylinder 115. In addition, such flow of air past the nozzle 157 draws oil through the conduit 165 from the reservoir 161, which discharged oil is carried to the cylinder 115 by the combustion air-fuel mixture.

If desired, a restriction 167 can be incorporated in the conduit 165 to increase the pumping action or discharge flow from the reservoir 161 to the cylinder 115.

The engine 211 shown in FIGURE 3 is similar to the engine 111 except that the reservoir 261 is not open to the atmosphere. Instead, the conduit or line 249 is provided with a resiliently expandable portion or bellows 269 to accommodate such increased pressure and increased volume as may accompany discharge from the crankcase. If desired, the reservoir 2 51 could include a resiliently expandable portion rather than the bellows 267 in the line 249.

in some two stroke engines, a pressure differential exists between the inlet valve supplying the crankcase with combustion air-fuel mixture and the inlet port at the cylinder end of the transfer passage. This pressure differential can be utilized with a single check valve to provide flow from a sump located adjacent the inlet valve to the inlet port at the cylinder.

Various of the features of the invention are set forth in the following claims.

What is claimed is:

1. In an internal combustion engine including a generally closed crankcase adapted to receive a combustion air-fuel mixture during a condition of low pressure, a cylinder extending from said crankcase, a piston reciprocably movable in said cylinder, whereby there is alternately developed in said crankcase a low pressure condition as said piston approaches top dead center and a high pressure condition as said piston approaches bottom dead center, and a bypass passage extending from said crankcase to said cylinder to permit entry of said mixture into said cylinder when said piston is adjacent bottom dead center, the improvement comprising means for pumping liquids accumulated in said crankcase into said cylinder at a point located between said piston and the opposed end of said cylinder as determined when said piston is at bottom dead center in response to cyclical variation of pressure in said crankcase and including conduit means communicating between the area of liquid accumulation in said crankcase and said point.

2. In an internal combustion engine including a generally closed crankcase adapted to receive a combustion air-fuel mixture during a condition of low pressure, a cylinder extending from said crankcase, a piston reciprocably movable in said cylinder whereby there is alternatively developed in said crankcase a low pressure condition as said piston approaches top dead center and a high pressure condition as said piston approaches bottom dead center, and a bypass passage extending from said crankcase to said cylinder to permit entry of said mixture into said cylinder when said piston is adjacent bottom dead center, and means for pumping liquids accumulated in said crankcase into said cylinder in response to cyclical variation of pressure in said crankcase, said means for atfording pumping of accumulated liquid comprising a receiver,

first conduit means communicating-with said receiver and with said crankcase in the area of liquid accumulation and including a check valve preventing flow from said receiver to said crankcase during a low pressure condition in said crankcase and permitting flow of the accumulated liquid from said crankcase to said receiver during a high pressure condition in said crankcase, and

second conduit means communicating with said bypass passage and with said receiver and including a check valve preventing flow of the accumulated liquid from said receiver to said bypass passage during a high pressure condition in said bypass passage and permitting fiow of the accumulated liquid from said receiver to said bypass passage during a low pressure condition in said bypass passage.

3. An improvement in accordance with claim 2 wherein said receiver includes means communicating with the interior thereof and with the atmosphere.

4. An improvement in accordance with claim 2 wherein one of said first conduit means and said receiver includes a resilient portion which expands when subject to increased pressure conditions.

5. An improvement in accordance with claim 2 wherein said second conduit means includes a restriction.

6. An improvement in accordance with claim 2 wherein said cylinder includes a wall having an inlet port at the end of said bypass passage, and

said second conduit means opens in said inlet port.

7. In an internal combustion engine including a pair of generally closed separate crankcases each adapted to receive a combustion air-fuel mixture during a condition of low pressure, separate cylinders extending from each of said crankcases, separate oppositely acting pistons reciprocably movable in each of said cylinders, whereby there is alternately developed in said crankcases a low pressure condition as the associated one of said pistons approaches top dead center and a high pressure condition as the associated one of said pistons approaches bottom dead center, and separate bypass passages extending from each of said crankcases to said cylinder extending therefrom to permit entry of said mixture therein when said associated piston is adjacent bottom dead center, the improvement comprising means for pumping liquids accumulated in said crankcases into said respective cylinders at respective points located between said pistons and the opposed ends of said respective cylinders as determined when said pistons are at bottom dead center in response to the cyclical variation in pressure in said crankcases and including respective conduit means communicating between the area of liquid accumulation in the respective crankcases and said points.

8. In an internal combustion engine including a pair of generally closed separate crankcases each adapted to receive a combustion air-fuel mixture during a condition of low pressure, separate cylinders extending from each of said crankcases, separate oppositely acting pistons reciprocably movable in each of said cylinders, whereby there is alternately developed in said crankcases a low pressure condition as the associated one of said pistons approaches top dead center and a high pressure condition as the associated one of said pistons approaches bottom dead center, separate bypass passages extending from each of said crankcases to said cylinder extending therefrom to permit entry of said mixture therein when said associated piston is adjacent bottom dead center, and means for pumping liquids accumulated in said crankcases into said cylinders in response to the cyclical variation in pressure in said crankcases, said means for pumping accumulated liquid comprising separate conduits connectingeach one of said crankcases to said bypass passage extending from the other of said crankcases, each of said conduits including a check valve preventing flow to the connected one of said crankcases during a low pressure condition in said connected crankcase and permitting flow of accumulated liquid from said connected crankcase to the connected one of said bypass passages during a high pressure condition in said connected crankcase.

9. An improvement in accordance with claim 8 wherein said cylinders each include a wall having an inlet port at the end of the associated bypass passage, and

said conduits each include a restriction and opens in said inlet port.

10. In an internal combustion engine including a pair of generally closed separate crankcases each adapted to receive a combustion air-fuel mixture during a condition of low pressure, separate cylinders extending from each of said crankcases, separate oppositely acting pistons reciprocably movable in each of said cylinders, whereby there is alternately developed in said crankcases a low pressure condition as the associated one of said pistons approaches top dead center and a high pressure condition as the associated one of said pistons approaches bottom dead center, separate bypass passages extending from each of said crankcases to said cylinder extending therefrom to permit entry of said mixture therein when said associated piston is adjacent bottom dead center, and means for pumping liquids accumulated in said crankcases into said cylinders in response to the cyclical variation in pressure in said crankcases,

said means for pumping accumulated liquid comprising separate means associated with each one of said crankcases, each of said separate means comprising a receiver, first conduit means communicating with said receiver and with the associated one of said crankcases in the area of liquid accumulation and including a check valve preventing flow from said receiver to said associated crankcase during a low pressure condition in said associated crankcase and permitting flow from said associated crankcase to said receiver during a high pressure condition in said associated crankcase, and

second conduit means communicating with said receiver and with said bypass passage extending from said associated crankcase and including a check valve preventing flow of liquid from said second conduit to said receiver and permitting flow of the accumulated liquid in said receiver from said receiver to said bypass passage extending from said associated crankcase during a low pressure condition in said bypass passage extending from said associated crankcase.

11. An internal combustion engine including a generally closed crankcase adapted to receive combustion air during a condition of low pressure,

a cylinder extending from said crankcase,

a piston reciprocably movable in said cylinder, whereby there is alternately developed in said crankcase a low pressure condition as said piston approaches top dead center and a high pressure condition as said piston approaches bottom dead center,

a bypass passage extending from said crankcase to said cylinder to permit entry of said combustion air into said cylinder when said piston is adjacent bottom dead center, and

means for pumping liquids accumulated in said crankcase into said cylinder at a point located between said piston and the opposed end of said cylinder as determined when said piston is at bottom dead center in response to cyclical variation of pressure in said crankcase and including conduit means communicating between the area of liquid accumulation in said crankcase and said point.

12. An internal combustion engine including a pair of generally closed separate crankcases each adapted to receive combustion air during a condition of low pressure,

separate cylinders extending from each of said crankcases,

separate oppositely acting pistons reciprocably movable in each of said cylinders, whereby there is alternately developed in said crankcases a low pressure condition as the associated one of said pistons approaches top dead center and a high pressure condition as the associated one of said pistons approaches bottom dead center,

separate bypass passages extending from each of said .crankcases to said cylinder extending therefrom to permit entry of said combustion air therein when said associated piston is adjacent bottom dead center, and

means for pumping liquids accumulated in said crankcases into said respective cylinders at respective points located between said pistons and the opposed ends of said respective cylinders as determined when said pistons are at bottom dead center in response to the cyclical variation in pressure in said crankcases and including respective conduit means communicating between the area of liquid accumulation in the respective crankcases and said points.

References Cited in the file of this patent UNITED STATES PATENTS 632,814 Hay et a1. Sept. 12, 1899 2,682,259 Watkins June 29, 1954 2,717,584 Upton Sept. 13, 1955 

1. IN AN INTERNAL COMBUSTION ENGINE INCLUDING A GENERALLY CLOSED CRANKCASE ADAPTED TO RECEIVE A COMBUSTION AIR-FUEL MIXTURE DURING A CONDITION OF LOW PRESSURE, A CYLINDER EXTENDING FROM SAID CRANKCASE, A PISTON RECIPROCABLY MOVABLE IN SAID CYLINDER, WHEREBY THERE IS ALTERNATELY DEVELOPED IN SAID CRANKCASE A LOW PRESSURE CONDITION AS SAID PISTON APPROACHES TOP DEAD CENTER AND A HIGH PRESSURE CONDITION AS SAID PISTON APPROACHES BOTTOM DEAD CENTER, AND A BYPASS PASSAGE EXTENDING FROM SAID CRANKCASE TO SAID CYLINDER TO PERMIT ENTRY OF SAID MIXTURE INTO SAID CYLINDER WHEN SAID PISTON IS ADJACENT BOTTOM DEAD CENTER, THE IMPROVEMENT COMPRISING MEANS FOR PUMPING LIQUIDS ACCUMULATED IN SAID CRANKCASE INTO SAID CYLINDER AT A POINT LOCATED BETWEEN SAID PISTON AND THE OPPOSED END OF SAID CYLINDER AS DETERMINED WHEN SAID PISTON IS AT BOTTOM DEAD CENTER IN RESPONSE TO CYCLICAL VARIATION OF PRESSURE IN SAID CRANKCASE AND INCLUDING CONDUIT MEANS COMMUNICATING BETWEEN THE AREA OF LIQUID ACCUMULATION IN SAID CRANKCASE AND SAID POINT. 